Concise total syntheses of (+)-strictifolione and (6R)-6-[(4R,6R)-4,6-dihydroxy-10-phenyldec-1-enyl]-5,6-dihydro-2H-pyran-2-one

Concise and efficient asymmetric total syntheses of (+)-strictifolione 1 and (6R)-6-[(4R,6R)-4,6-dihydroxy-10-phenyldec-1-enyl]-5,6-dihydro-2H-pyran-2-one 2 have been achieved based on the strategic application of one-pot double allylboration and ring-closing metathesis reactions. The total syntheses proceeded in only five and seven steps, respectively, from readily available 3-butenal and represent the shortest syntheses of 1 and 2 reported to date.     

Stereoselective total synthesis of (+)-strictifolione and (6R)-6[(E,4R,6R)-4,6-dihydro-10-phenyl-1-decenyl)-5,6-dihydro-2H-2-pyrone

The stereoselective total synthesis of two naturally occurring α-pyrone derivatives, (+)-strictifolione and (6R)-6[(E,4R,6R)-4,6-dihydroxy-10-phenyl-1-decanyl]-5,6-dihydro-2H-2-pyrone has been accomplished involving the Sharpless kinetic resolution and olefin cross-metathesis as the key reactions.     

First stereoselective total synthesis of (6R)-6-[(4R,6R)-4,6-dihydroxy-10-phenyldec-1-enyl]-5,6-dihydro-2H-pyran-2-one

A stereoselective total synthesis of (6R)-6-[(4R,6R)-4,6-dihydroxy-10-phenyldec-1-enyl]-5,6-dihydro-2H-pyran-2-one is reported. The strategy utilizes an iterative Jacobsen hydrolytic kinetic resolution, ring opening with a chiral propargylic synthon and a preferential (Z)-Wittig olefination reaction and lactonization as the key steps.     

Stereoselective synthesis of (6S)-5,6-dihydro-6-[(2R)-2-hydroxy-6-phenylhexyl]-2H-pyran-2-one

A stereoselective synthesis of (6S)-5,6-dihydro-6-[(2R)-2-hydroxy-6-phenylhexyl]-2H-pyran-2-one is reported. The strategy utilizes an olefin cross-metathesis, syn-benzylidene acetal formation and a preferential (Z)-Wittig olefination reaction and lactonization as the key steps.     

An organocatalytic route to the synthesis of (6S)-5,6-dihydro-6-[(2R)-2-hydroxy-6-phenylhexyl]-2H-pyran-2-one and ravensara lactones

An organocatalytic enantioselective synthesis of the title compounds has been achieved. The stereogenic centers were generated by the iterative use of proline catalyzed α-aminoxylations and HWE olefination of aldehydes while the lactone ring was constructed by ring closing metathesis.     

2,3-二氢-3,5-二羟基-6-甲基-4(H)吡喃-4-酮的合成及热裂解行为

以葡萄糖和哌啶为原料，合成、分离并鉴定了2，3－二氢－3，5－二羟基－6－甲基－4－（H）吡喃－4－酮（1），以空气氛下直接热裂解，SPME吸附热裂解挥发生产物的方式，分析鉴定了20个裂解的挥发性化合物，讨论了热裂解的可能过程。     

The first stereoselective total synthesis of (6S)-5,6-dihydro-6-[(2R)-2-hydroxy-6-phenylhexyl]-2H-pyran-2-one

Iterative asymmetric allylations and ring-closing metathesis have been effectively performed for the first stereoselective total synthesis of (6S)-5,6-dihydro-6-[(2R)-2-hydroxy-6-phenylhexyl]-2H-pyran-2-one, a novel α,β-unsaturated-δ-lactone having antifungal activity, isolated from Ravensara crassifolia.     

Chemoenzymatic preparation of (6R)-5,6-dihydro-2H-pyran-2-one: a ubiquitous structural motif of biologically active lactones

A chemoenzymatic synthesis of an enantiopure 6-substituted 5,6-dihydro-2H-pyran-2-one using bromobenzene as a starting material is presented. This important structural motif is found in a large number of chiral lactones that present a wide range of biological activities. The key features of the preparation include enzymatic dioxygenation of bromobenzene using Escherichia coli JM109 (pDTG601), microwave-assisted acyloin cleavage, and tin mediated lactonization. The stereochemical assignment for the alcohol was confirmed by NMR analysis of Moshe?s derivatives.     

Synthesis of 2[(4,6-diphenyl-2H-pyran-2-ylidene)methyl]-4,6-diphenylpyrylium perchlorate

The title compound was prepared by the condensation of 4,6-diphenyl-2H-pyran-2-one and acetophenone in phosphorus oxychloride. The absorption spectrum of this 2,2-methine dye is compared with those of the corresponding 2,4- and 4,4-methine dyes.     

Stereoselective synthesis of new (+)-1-{(1R,3R,6S)-4,7,7-trimethylbicyclo[4.1.0]hept-4-en-3-yl}ethan-1-one derivatives

A procedure was developed for the stereoselective synthesis of aminated derivatives of (+)-1-{(1R,3R,6S)-4,7,7-trimethylbicyclo[4.1.0]hept-4-en-3-yl}ethan-1-one. The configuration of the side-chain chiral center in (+)-1-{(1R,3R,6S)-4,7,7-trimethylbicyclo[4.1.0]hept-4-en-3-yl}ethan-1-ol was determined by X-ray analysis. Diketene and Meldrum’s acid were proposed as initial compounds for the synthesis of, respectively, 3-oxobutanoic and malonic acid esters having a 1-ethyl-4,7,7-trimethylbicyclo[4.1.0]hept-4-ene fragment.     

Stereoselective synthesis of (6S) and (6R)-5,6-dihydro-6-[(2R)-2-hydroxy-6-phenylhexyl]-2H-pyran-2-one and their cytotoxic activity against cancer cell lines

Stereoselective total synthesis of α,β-unsaturated lactone (1a), isolated from Ravensara crassifolia, has been achieved efficiently starting from chiral 2,3-O-isopropylidene-d-glyceraldehyde (3) followed by asymmetric allylation and ring-closing metathesis. The antiproliferative activities of compounds 1a, 1b and the unusual bicyclic compound 2 were evaluated against three-cancer cell lines, THP-1 and U-937 (leukemia) and A-375 (melanoma).     

(4R,6R)-6-(hydroxymethyl)-4-methyltetrahydro-2H-pyran-2-one in the synthesis of polyfunctional compounds with the methyl-branched carbon skeleton

A simple and efficient asymmetrical synthesis was performed of a convenient bifunctional building block, methyl (R)-5,5-dimethoxy-3-methylpentanoate and its (S)-enantiomer. The possibility was shown of its application to the synthesis of insect pheromones.     

First total syntheses and absolute configuration of rugulactone and 6(R)-(4′-oxopent-2′-enyl)-5,6-dihydro-2H-pyran-2-one

The first efficient total syntheses of rugulactone and 6(R)-(4′-oxopent-2′-enyl)-5,6-dihydro-2H-pyran-2-one have been achieved in six steps with 51% and 48% overall yield, respectively. The key steps are Jacobsen’s hydrolytic kinetic resolution (HKR), Horner-Wadsworth-Emmons (HWE) homologation, and ring-closing metathesis reaction.     

Stereocontrolled total synthesis of the chiral building block (3S,4R)-3- [(R)-1-hydroxyethyl]-4-acetyloxy-azetidin-2-one: a useful synthon for the synthesis of (+)-thienamycin,carbapenems and penems.

A total stereocontrolled synthesis of ($\text{1}$), an intermediate in the synthesis of (+)-thienamycin, carbapenems and penems, based on a strategy that uses the S(-)hydroxy ethylbutyrate as chiral building block, is reported.     

Regio- and stereoselective synthesis of trichloro[(Z)-2-chloroalk-1-enyl]tellanes

Russian Journal of Organic Chemistry -     

Development of 5-[(3-aminopropyl)phosphinooxy]-2-(hydroxymethyl)-4H-pyran-4-one as a novel whitening agent

A stable derivative of kojic acid, 5-[(3-aminopropyl)phosphinooxy]-2-(hydroxymethyl)-4H-pyran-4-one (Kojyl-APPA), was synthesized in good yield. The effects of Kojyl-APPA on tyrosinase activity and melanin synthesis were investigated. Kojyl-APPA showed tyrosinase inhibition effect (30%) in situ, but not in vitro. Kojyl-APPA inhibited tyrosinase activity significantly at 24 h after treatment in normal human melanocytes. It means that Kojyl-APPA is not a direct inhibitor of tyrosinase itself, but it is converted to a potential inhibitor kojic acid enzymatically in cells. In addition, Kojyl-APPA decreased melanin content to 75% of control in melanoma cells and decreased neomelanin synthesis to 43% of control in normal human melanocytes. Its permeation through skin increased by about 8 times as compared with kojic acid.     

Enantioselective synthesis of (+)-(S)-7,8-dihydrokavain and (4R,6R)-4-hydroxy-6-(2-phenylethyl)tetrahydro-2H-pyran-2-one, lactone analog of compactin and mevinolin

A simple and efficient asymmetric synthesis was performed of (+)-(S)-7,8-dihydrokanian and (4R,6R)-4-hydroxy-6-(2-phenylethyl)tetrahydro-2H-pyran-2-one involving Keck allylation in the key stage of building up the carbon scaffold of the target molecules.